Download, unzip and save the file "com.steinberg.Virtual Guitarist 2.plist" in your user-level preferences folder. It can be found here:

System partition/Your Username/Library/Preferences

Please note: Since Mac OS X 10.7 (Lion), the user's Library folder is hidden! Here is how to access it: In the menu bar of Mac OS X click on 'Go'. While the menu is folded out, holding down the [alt] key (options) will show the "Library" entry.

Using a plain text editor (e.g. TextWrangler), open the .plist file and set the value of the "Data Path" key to the name of the folder that contains the Virtual Guitarist .dat files. Make sure to include the trailing slash, e.g. as in this excerpt:

Select the .plist file in the Finder and simultaneously press cmd + I to open the Get Info window. Alternatively, right-click on the file and select Get Info from the contextual menu.

In the Get Info window, under 'Sharing & Permissions', make sure 'Privilege' is set to 'Read & Write' for all three groups. You may need to click the lock at the bottom of the window to authenticate in order to make this change.

Now the Virtual Guitarist 2 content should be located correctly. The instructions also work for Virtual Bassist with the expected modifications in the name of the .plist file.